Which Compression Tester for IO-390?

[MS19087]

Getting ready for my condition inspection. Need to purchase a compression tester - what size orifice do i need?

Thanks!

 

[DanH]

That question and more

https://www.danhorton.net/Articles/0913_MaintMatters_Compression.pdf

 

[lipper03]

Great write up Dan! I got myself both a mag and compression tester for Christmas, have watched my AP/IA do it on my Dakota, and figured I better get in the game before my engine shows up for the 14A.